Sciene say no is an event that takes place...when Science says no. This happens when science cannot, will not, or has not allowed someone to do something stupid.
This theory, as you could call it was evented during a very weird roleplaying game headed by the Writer and played by Riodel. This being the same adventure that spawned Sharp Cheddar, the Hammersword and the ability to obtain a facesmmash(Bhnrgrgy).
Science says no when, it wants to. There's no active way to predict WHEN science will say no, but there are ways to tell when it MIGHT say no.
Science might say no when the suggestion goes completely against one of the Trio's wishes.
Science might say no when ALL YOUR BASE ARE BELONG TO US
Science might say no when ever it feels like it
You enter the room of atomic acceleration. There is a banana on the ground. There are also many shiny buttons. What will you do?
Lordike3: I eat the banana and press every single button while dancing in the bear suit and looking around cautiously!
You blow up into a million pieces because science said no. You lost the game. HAHAHAHAHAHAHA
Lordike3: DAMN YOU MURPHY'S LAWWWWWWWWWWWWWWWWWWWWWWWWWWWWW *boom*